Taurine-activated chloride currents in the rat sacral dorsal commissural neurons

Abstract

The electrophysiological and pharmacological properties of taurine (Tau)-activated Cl − currents ( I Tau) were investigated in the dissociated rat sacral dorsal commissural nucleus (SDCN) neurons using the nystatin perforated patch recording configuration under voltage-clamp conditions. The reversal potential of I Tau was close to the Cl − equilibrium potential. The I Tau was not affected by a preceding GABA response but cross-desensitized by a preceding glycine (Gly) response. Strychnine (STR), picrotoxin (PIC), bicuculline (BIC) and Zn 2+ suppressed the I Tau in a concentration-dependent manner. The pharmacology of the I Tau and Gly-induced response ( I Gly) was similar, though Zn 2+ inhibition on I Tau differed from that on I Gly in being much slower in recovery. Serotonin potentiated the I Tau via protein kinase C. The results indicate that both Tau and Gly act on a strychnine-sensitive site to open the same Cl − channels in the SDCN neurons, and suggest that Tau may act as a functional neurotransmitter in the mammalian SDCN.